Processing aid

ABSTRACT

The invention provides a processing aid enabling short-time disappearance of melt fracture occurred in extrusion-molding a melt-fabricable resin at a high shear rate, a great reduction in extrusion pressure, and production of molded articles with good appearance. The processing aid contains a polymer containing a fluorine-containing elastomeric polymer segment and a fluorine-containing non-elastomeric polymer segment.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional Application of U.S. application Ser.No. 15/503,102 filed on Feb. 10, 2017, which is a National Stage ofInternational Application No. PCT/JP2015/072507 filed Aug. 7, 2015,claiming priority based on Japanese Patent Application No. 2014-168578filed Aug. 21, 2014, the contents of all of which are incorporatedherein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to processing aids, molding compositions,processing aid masterbatches, and molded articles.

BACKGROUND ART

Achievement of higher productivity and lower cost in processingmelt-fabricable resins requires high-rate extrusion of melt-fabricableresins. However, melt-fabricable resin compositions inevitably have acritical shear rate and, if the extrusion rate is higher than thecritical shear rate, the surface of a product becomes roughened (thisphenomenon is called melt fracture), causing a failure in providingfavorable molded articles.

One example of methods that can solve such a problem to avoid meltfracture and achieve a higher extrusion rate to improve theextrudability is a method of molding a material at a higher moldingtemperature. However, high-temperature molding causes pyrolysis ofmelt-fabricable resins, which raises problems such as reduction inmechanical properties of molded articles and staining on moldedarticles. In addition, the melt-fabricable resins are caused to have alower melt viscosity, and thus drip off or deform before being cooledand solidified. This impairs the dimensional accuracy of moldedarticles.

Patent Literature 1 discloses, as another method, a method of producingan extrudable composition including the step of simultaneously mixing i)a first fluoroelastomer that has a first Mooney viscosity ML₍₁₊₁₀₎ at121° C. determined in conformity with ASTM D-1646 in an amount of 0.001to 10 wt % based on the total weight of the extrudable composition, ii)a second fluoroelastomer having a second Mooney viscosity ML₍₁₊₁₀₎ at121° C. determined in conformity with ASTM D-1646 in an amount of 0.001to 10 wt % based on the total weight of the extrudable composition, andiii) a non-fluorinated melt-fabricable polymer, with a differencebetween the first and second Mooney viscosities of at least 15.

Patent Literature 2 discloses a method including the steps of: preparinga melt-fabricable polymer composition that contains a melt-fabricablethermoplastic host polymer and an effective amount of an additivecomposition for processing that contains a specific multimodefluoropolymer; mixing the additive composition for processing and thehost polymer for a time enough for thorough mixing of them; andmelt-fabricating the polymer composition.

The following documents disclose techniques using a fluoropolymer as aprocessing aid. Patent Literature 3 discloses an extrudable compositioncontaining a thermoplastic hydrocarbon polymer, a poly(oxyalkylene)polymer, and a fluorocarbon polymer. Patent Literature 4 discloses anextrudable composition containing a resin blend that contains ametallocene linear low-density polyethylene resin and a low-densitypolyethylene resin, a fluoroelastomer that has a Mooney viscosityML₍₁₊₁₀₎ at 121° C. of 30 to 60, and a surfactant. Patent Literature 5discloses a processing aid containing a fluorine-containing polymer thathas an acid value of 0.5 KOHmg/g or higher.

Patent Literature 6 discloses a processing aid to be mixed with athermoplastic hydrocarbon polymer, containing a copolymer of afluorinated olefin monomer and a substantially non-fluorinatedhydrocarbon olefin monomer.

CITATION LIST Patent Literature

Patent Literature 1: JP 4181042 B

Patent Literature 2: JP 2002-544358 T

Patent Literature 3: JP H02-70737 A

Patent Literature 4: JP 2007-510003 T

Patent Literature 5: WO 2011/025052

Patent Literature 6: U.S. Pat. No. 5,710,217 B

SUMMARY OF INVENTION Technical Problem

The field of the art still demands processing aids enabling short-timedisappearance of melt fracture occurred in extrusion-molding amelt-fabricable resin at a high shear rate, as well as reduction inextrusion pressure and production of molded articles with goodappearance.

In view of the above state of the art, the present invention aims toprovide a processing aid enabling short-time disappearance of meltfracture occurred in extrusion-molding a melt-fabricable resin at a highshear rate, a great reduction in extrusion pressure, and production ofmolded articles with good appearance.

Solution to Problem

The inventors examined various means for solving the above problems tofind that the above problems can be solved by a processing aidcontaining a fluorine-containing segmented polymer containing anelastomeric segment and a non-elastomeric segment, thereby completingthe present invention.

Specifically, the present invention relates to a processing aidcontaining a polymer containing a fluorine-containing elastomericpolymer segment and a fluorine-containing non-elastomeric polymersegment.

The fluorine-containing elastomeric polymer segment is preferably asegment derived from at least one fluorine-containing elastomericpolymer selected from the group consisting of vinylidenefluoride/hexafluoropropylene copolymers, vinylidenefluoride/tetrafluoroethylene/hexafluoropropylene copolymers, vinylidenefluoride/perfluoro(alkyl vinyl ether) copolymers, vinylidenefluoride/tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymers,vinylidene fluoride/hexafluoropropylene/perfluoro(alkyl vinyl ether)copolymers, vinylidene fluoride/chlorotrifluoroethylene copolymers,tetrafluoroethylene/propylene copolymers, andtetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymers.

The fluorine-containing non-elastomeric polymer segment is preferably asegment derived from at least one fluorine-containing non-elastomericpolymer selected from the group consisting oftetrafluoroethylene/hexafluoropropylene copolymers,tetrafluoroethylene/ethylene copolymers,ethylene/tetrafluoroethylene/monomer (a) copolymers, vinylidenefluoride/tetrafluoroethylene copolymers, vinylidenefluoride/hexafluoropropylene copolymers, vinylidenefluoride/chlorotrifluoroethylene copolymers, polytetrafluoroethylene,polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinylfluoride, chlorotrifluoroethylene/tetrafluoroethylene copolymers,chlorotrifluoroethylene/ethylene copolymers, andtetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymers.

The polymer is preferably a block polymer or a graft polymer.

The processing aid preferably further contains 1 to 99 mass % of asurfactant.

The surfactant is preferably at least one compound selected from thegroup consisting of silicone-polyether copolymers, aliphatic polyesters,aromatic polyesters, polyether polyols, amine oxides, carboxylic acids,aliphatic esters, and poly(oxyalkylenes), more preferably apoly(oxyalkylene), still more preferably polyethylene glycol.

The processing aid also preferably further contains 1 to 30 parts bymass of an anti-reagglomerating agent relative to 100 parts by mass ofthe polymer.

The anti-reagglomerating agent is preferably at least one selected fromthe group consisting of talc, silica, and calcium carbonate.

The present invention also relates to a processing aid masterbatchcontaining the above processing aid and a melt-fabricable resin, thepolymer being contained in an amount more than 0.1 mass % but not morethan 20 mass % of the sum of masses of the polymer and themelt-fabricable resin.

The melt-fabricable resin is preferably a polyolefin resin.

The present invention also relates to a molding composition containingthe above processing aid and a melt-fabricable resin, the polymer beingcontained in an amount of 0.0001 to 10 mass % of the sum of masses ofthe processing aid and the melt-fabricable resin.

The melt-fabricable resin is preferably a polyolefin resin.

The present invention also relates to a molded article obtainable bymolding the above molding composition.

Advantageous Effects of Invention

The processing aid of the present invention enables short-timedisappearance of melt fracture occurred in extrusion-molding amelt-fabricable resin at a high shear rate, a great reduction inextrusion pressure, and production of molded articles with goodappearance. The processing aid is also expected to restrainsedimentation of die drool (die build up) at ejection nozzle tips ofdies of extrusion-molding devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a chart of die pressure changes over time in extrusion ofExamples 1 to 3 and Comparative Examples 1 to 4.

FIG. 2 is a chart of die pressure changes over time in extrusion ofExample 4 and Comparative Examples 5 to 8.

FIG. 3 is a chart of die pressure changes over time in extrusion ofExample 5 and Comparative Examples 9 to 12.

FIG. 4 is a chart of die pressure changes over time in extrusion ofExample 6 and Comparative Examples 13 to 16.

DESCRIPTION OF EMBODIMENTS

The present invention will be specifically described hereinbelow.

The processing aid of the present invention contains a polymercontaining a fluorine-containing elastomeric polymer segment and afluorine-containing non-elastomeric polymer segment.

The fluorine-containing elastomeric polymer segment preferably has aunit derived from at least one fluoromonomer selected from the groupconsisting of tetrafluoroethylene (TFE), hexafluoropropylene (HFP),chlorotrifluoroethylene (CTFE), vinyl fluoride, vinylidene fluoride(VDF), trifluoroethylene, hexafluoroisobutylene, monomers represented byCH₂═CZ¹(CF₂)_(n)Z² (where Z¹ is H or F; Z² is H, F, or Cl; and n is aninteger of 1 to 10), perfluoro(alkyl vinyl ethers) (PAVEs) representedby CF₂═CF—ORf⁶ (where Rf⁶ is a C1-C8 perfluoroalkyl group), and alkylperfluorovinyl ether derivatives represented by CF₂═CF—O—CH₂—Rf⁷ (whereRf⁷ is a C1-C5 perfluoroalkyl group).

The fluorine-containing elastomeric polymer segment preferably has a VDFunit or a TFE unit, more preferably has a VDF unit.

The proportion of the VDF unit is preferably 30 to 85 mol %, morepreferably 50 to 80 mol %, relative to all the monomer unitsconstituting the fluorine-containing elastomeric polymer segment. If thefluorine-containing elastomeric polymer segment has no VDF unit, theproportion of the TFE unit is preferably 45 to 90 mol %, more preferably55 to 70 mol %, relative to all the monomer units constituting thefluorine-containing elastomeric polymer segment.

The fluorine-containing elastomeric polymer segment is preferably asegment derived from at least one fluorine-containing elastomericpolymer selected from the group consisting of VDF/HFP copolymers,VDF/TFE/HFP copolymers, VDF/TFE/2,3,3,3-tetrafluoro-1-propenecopolymers, VDF/PAVE copolymers, VDF/TFE/PAVE copolymers, VDF/HFP/PAVEcopolymers, VDF/CTFE copolymers, VDF/2,3,3,3-tetrafluoro-1-propenecopolymers, TFE/propylene copolymers, and TFE/PAVE copolymers.

The VDF/HFP copolymers preferably have a VDF/HFP ratio of (45 to 85)/(55to 15) (mol %), more preferably (50 to 80)/(50 to 20) (mol %), stillmore preferably (60 to 80)/(40 to 20) (mol %).

The VDF/TFE/HFP copolymers preferably have a VDF/TFE/HFP ratio of (30 to80)/(4 to 35)/(10 to 35) (mol %).

The VDF/TFE/2,3,3,3-tetrafluoro-1-propene copolymers preferably have aVDF/TFE/2,3,3,3-tetrafluoro-1-propene ratio of (30 to 80)/(4 to 35)/(10to 35) (mol %).

The VDF/PAVE copolymers preferably have a VDF/PAVE ratio of (65 to90)/(35 to 10) (mol %).

The VDF/TFE/PAVE copolymers preferably have a VDF/TFE/PAVE ratio of (40to 80)/(3 to 40)/(15 to 35) (mol %).

The VDF/HFP/PAVE copolymers preferably have a VDF/HFP/PAVE ratio of (65to 90)/(3 to 25)/(3 to 25) (mol %).

The VDF/CTFE copolymers preferably have a VDF/CTFE ratio of (30 to90)/(70 to 10) (mol %).

The VDF/2,3,3,3-tetrafluoro-1-propene copolymers preferably have aVDF/2,3,3,3-tetrafluoro-1-propene copolymer ratio of (30 to 90)/(70 to10) (mol %).

The TFE/propylene copolymers preferably have a TFE/propylene ratio of(45 to 90)/(55 to 10) (mol %).

The TFE/PAVE copolymers preferably have a TFE/PAVE ratio of (65 to90)/(35 to 10) (mol %).

The fluorine-containing elastomeric polymer segment is preferably asegment derived from a copolymer containing a VDF unit, more preferablya segment derived from at least one fluorine-containing elastomericpolymer selected from the group consisting of VDF/HFP copolymers,VDF/HFP/TFE copolymers, VDF/2,3,3,3-tetrafluoro-1-propene copolymers,and VDF/TFE/2,3,3,3-tetrafluoro-1-propene copolymers, still morepreferably a segment derived from at least one fluorine-containingelastomeric polymer selected from the group consisting of VDF/HFPcopolymers and VDF/HFP/TFE copolymers.

The fluorine-containing elastomeric polymer segment preferably has aMooney viscosity ML₍₁₊₁₀₎ of 10 to 100. The Mooney viscosity ML₍₁₊₁₀₎ ismore preferably 20 or higher, still more preferably 30 or higher, whilemore preferably 80 or lower, still more preferably 60 or lower.

The Mooney viscosity ML₍₁₊₁₀₎ can be determined at 121° C. using aMooney viscometer MV2000E (Alpha Technologies Inc.) in conformity withASTM D-1646.

The fluorine-containing elastomeric polymer segment preferably has aglass transition temperature of −70° C. or higher, more preferably −60°C. or higher, still more preferably −50° C. or higher, while preferably5° C. or lower, more preferably 0° C. or lower, still more preferably−3° C. or lower.

The glass transition temperature can be determined as follows.Specifically, 10 mg of a sample is heated at 10° C./min using adifferential scanning calorimeter (DSC822e, Mettler-Toledo InternationalInc.) to provide a DSC curve, and the temperature indicated by themiddle point of two intersections between each of the extended lines ofthe base lines before and after the secondary transition on the DSCcurve and the tangent at the inflection point on the DSC curve isdefined as the glass transition temperature.

The fluorine-containing non-elastomeric polymer segment preferably has aunit derived from at least one fluoromonomer selected from the groupconsisting of tetrafluoroethylene (TFE), hexafluoropropylene (HFP),chlorotrifluoroethylene (CTFE), vinyl fluoride, vinylidene fluoride(VDF), trifluoroethylene, hexafluoroisobutylene, monomers represented byCH₂═CZ¹(CF₂)_(n)Z² (where Z¹ is H or F; Z² is H, F, or Cl; and n is aninteger of 1 to 10), perfluoro(alkyl vinyl ethers) (PAVEs) representedby CF₂═CF—ORf⁶ (where Rf⁶ is a C1-C8 perfluoroalkyl group), and alkylperfluorovinyl ether derivatives represented by CF₂═CF—O—CH₂—Rf⁷ (whereRf⁷ is a C1-05 perfluoroalkyl group).

The fluorine-containing non-elastomeric polymer segment preferably has aVDF unit, a TFE unit, or a CTFE unit, more preferably has a VDF unit ora TFE unit.

The proportion of the VDF unit is preferably 20 to 100 mol %, morepreferably 40 to 100 mol %, relative to all the monomer unitsconstituting the fluorine-containing non-elastomeric polymer segment.The proportion of the TFE unit is preferably 20 to 100 mol %, morepreferably 40 to 100 mol %, relative to all the monomer unitsconstituting the fluorine-containing non-elastomeric polymer segment.

The fluorine-containing non-elastomeric polymer segment is preferably asegment derived from at least one fluorine-containing non-elastomericpolymer selected from the group consisting of TFE/HFP copolymers,TFE/ethylene copolymers, ethylene/TFE/monomer (a) copolymers, VDF/TFEcopolymers, polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene(PCTFE), polyvinylidene fluoride (PVDF), VDF/HFP copolymers, VDF/CTFEcopolymers, polyvinyl fluoride, CTFE/TFE copolymers, CTFE/ethylenecopolymers, and TFE/PAVE copolymers.

The monomer (a) is preferably a monomer copolymerizable with TFE andethylene, and preferably at least one selected from the group consistingof HFP, pentafluoropropylene, 3,3,3-trifluoropropylene-1,2-trifluoromethyl-3,3,3-trifluoropropylene-1, PAVE,(perfluoroalkyl)ethylenes, and compounds represented byCH₂═CX—(CF₂)_(n)Z (where X and Z may be the same as or different fromeach other, and are individually a hydrogen atom or a fluorine atom; andn is an integer of 2 to 8). Examples of the (perfluoroalkyl)ethylenesinclude (perfluorobutyl)ethylene and (perfluorohexyl)ethylene. Examplesof the compounds represented by CH₂═CX—(CF₂)_(n)Z includeCH₂═CFCF₂CF₂CF₂H and CH₂═CFCF₂CF₂CF₂CF₂CF₂H.

The TFE/ethylene copolymers preferably have a TFE/ethylene ratio of (20to 90)/(80 to 10) (mol %), more preferably (37 to 85)/(63 to 15) (mol%), still more preferably (38 to 80)/(62 to 20) (mol %).

The ethylene/TFE/monomer (a) ratio is preferably (79.9 to 10)/(20 to89.9)/(0.1 to 14) (mol %), more preferably (62.9 to 15)/(37 to84.9)/(0.1 to 10) (mol %), still more preferably (61.8 to 20)/(38 to79.8)/(0.2 to 8) (mol %).

The VDF/TFE copolymers preferably have a VDF/TFE ratio of (0.1 to99.9)/(99.9 to 0.1) (mol %), more preferably (10 to 90)/(90 to 10) (mol%).

The VDF/HFP copolymers preferably have a VDF/HFP ratio of (70 to99.9)/(30 to 0.1) (mol %), more preferably (85 to 99.9)/(15 to 0.1) (mol%).

The VDF/CTFE copolymers preferably have a VDF/CTFE ratio of (70 to99.9)/(30 to 0.1) (mol %), more preferably (85 to 99.9)/(15 to 0.1) (mol%).

The fluorine-containing non-elastomeric polymer segment is morepreferably a segment derived from at least one fluorine-containingnon-elastomeric polymer selected from the group consisting ofTFE/ethylene copolymers, ethylene/TFE/monomer (a) copolymers, PVDF,VDF/TFE copolymers, CTFE/ethylene copolymers, and CTFE/ethylene/monomer(a) copolymers.

In order to enjoy the effects in extrusion molding not only at a highshear rate but also at a low shear rate, the fluorine-containingnon-elastomeric polymer segment is preferably a segment derived from atleast one fluorine-containing non-elastomeric polymer selected from thegroup consisting of PVDF, VDF/HFP copolymers, VDF/CTFE copolymers, andVDF/TFE copolymers.

Since conventional processing aids improve the extrudability only withina narrow shear rate range and have respective optimal shear rate ranges,users need to choose an optimal processing aid for the target shearrate. Thus, they demand a processing aid enabling, regardless of theshear rate level, disappearance of melt fracture in a shorter time, aswell as reduction in extrusion pressure and production of moldedarticles with good appearance. The inventors have performed studies tofind that a fluorine-containing non-elastomeric polymer having a segmentderived from the above polymer leads to excellent effects regardless ofthe shear rate level.

The polymer may be a block polymer or a graft polymer.

The block polymer is preferably one represented by the formula:Q-[(A-B— . . . )I]_(n)(wherein Q is a residue after separation of an iodine atom from aniodide compound; A, B, . . . are polymer chain segments (at least one ofthem is a fluorine-containing elastomeric polymer segment and at leastone of them is a fluorine-containing non-elastomeric polymer segment); Iis the iodine atom isolated from the iodide compound; and n is thevalence of Q). The block polymer preferably essentially includes a chainconsisting of at least two polymer chain segments, an iodine atom, and aresidue after separation of at least one iodine atom from an iodidecompound, the iodine atom and the residue bonding to the respective endsof the chain.

Examples of the iodide compound include monoiodoperfluoromethane,2-iodo-1-hydroperfluoroethane, 2-iodoperfluoropropane,1,4-diiodoperfluorobutane, 1,3-diiodoperfluoropropane,2-chloro-1,3-diiodoperfluoropropane,2,4-dichloro-1,5-diiodoperfluoropentane, and 4-iodoperfluorobutene-1.

Examples of the block polymer include polymers having a chain of(fluorine-containing elastomeric polymer segment)-(fluorine-containingnon-elastomeric polymer segment), polymers having a chain of(fluorine-containing elastomeric polymer segment)-(fluorine-containingnon-elastomeric polymer segment)-(fluorine-containing elastomericpolymer segment), and polymers having a chain of (fluorine-containingnon-elastomeric polymer segment)-(fluorine-containing elastomericpolymer segment)-(fluorine-containing non-elastomeric polymer segment).

The block polymer is obtainable by a known method. Examples of such amethod include a method including radical-polymerizing a fluoromonomerin the presence of an iodide compound to provide a fluorine-containingelastomeric polymer in which an iodine atom bonds to at least one end,and then radical-polymerizing a fluoromonomer to the fluorine-containingelastomeric polymer to provide a polymer containing afluorine-containing elastomeric polymer segment and afluorine-containing non-elastomeric polymer segment. If necessary,another fluoromonomer may be radical-polymerized to the polymer toprovide a polymer having a third segment. Production methods disclosedin JP S62-21805 B and JP S63-59405 B may also be used.

Examples of the graft polymer include polymers obtainable by aproduction method including radical-copolymerizing a fluoromonomer and amonomer having both a double bond and a peroxide bond in the molecule toprovide a fluorine-containing elastomeric polymer serving as a mainchain polymer and graft-polymerizing a fluoromonomer in the presence ofthe fluorine-containing elastomeric polymer.

Examples of the monomer having both a double bond and a peroxide bond inthe molecule include t-butyl peroxymethacrylate,di(t-butylperoxy)fumarate, t-butyl peroxycrotonate, t-butyl peroxyallylcarbonate, t-hexyl peroxyallyl carbonate, 1,1,3,3-tetramethylperoxyallyl carbonate, t-butyl peroxymetallyl carbonate,1,1,3,3-tetramethylbutyl peroxymetallyl carbonate, p-menthaneperoxyallyl carbonate, and p-menthane peroxymetallyl carbonate.

The graft polymer may be produced by methods disclosed in JP H02-305844A and JP H03-139547 A.

The polymer preferably satisfies the ratio of SS to the sum of SS and HS(SS/(SS+HS), where SS means the fluorine-containing elastomeric polymersegment and HS means the fluorine-containing non-elastomeric polymersegment) is 1 to 99, more preferably 50 or higher, still more preferably60 or higher, while more preferably 90 or lower, still more preferably80 or lower. If the proportion of the fluorine-containing elastomericpolymer segment is too high, the resulting processing aid may fail tosufficiently reduce the extrusion pressure at a high shear rate. If theproportion of the fluorine-containing non-elastomeric polymer segment istoo high, the resulting processing aid may fail to sufficiently reducethe extrusion pressure at a low shear rate.

The polymer preferably has a melting point of 120° C. to 280° C., morepreferably 140° C. or higher, still more preferably 160° C. or higher,while more preferably 270° C. or lower, still more preferably 230° C. orlower.

The melting point is the temperature corresponding to the maximum valueon a heat-of-fusion curve obtained using a differential scanningcalorimeter (DSC) at a temperature-increasing rate of 10° C./min.

The polymer preferably has a melt flow rate (MFR) of 0.1 to 80 g/10 min.The MFR is more preferably 0.5 or higher, still more preferably 1 orhigher, while more preferably 50 or lower, still more preferably 30 orlower.

The MFR is determined at an appropriate temperature corresponding to themelting point of the fluorine-containing non-elastomeric polymersegment. If the fluorine-containing non-elastomeric polymer segment isan ethylene/TFE/monomer (a) copolymer, the MFR can be determined at 250°C. If the fluorine-containing non-elastomeric polymer segment ispolyvinylidene fluoride (PVDF), the MFR can be determined at 230° C.

In one preferred embodiment, the processing aid of the present inventioncontains a surfactant in addition to the above polymer. Such combinationuse of the polymer with a surfactant can lead, even in a reduced amountof the polymer, to the performance of the processing aid equal to orhigher than that achieved without a surfactant.

The surfactant, if contained in the molding composition to be mentionedlater, is preferably a compound that has a lower melt viscosity than themelt-fabricable resin at a molding temperature and can wet the surfaceof the polymer. The surfactant and the melt-fabricable resin aredifferent compounds.

The surfactant is preferably at least one surfactant selected from thegroup consisting of silicone-polyether copolymers, aliphatic polyesters,aromatic polyesters, polyether polyols, amine oxides, carboxylic acids,aliphatic esters, and poly(oxyalkylenes). These surfactants have a lowermelt viscosity than the polymer. Thus, the surfactant, when mixed withthe polymer, can wet the surface of the polymer, sufficiently serving asa surfactant. More preferred are poly(oxyalkylenes).

Preferred among the poly(oxyalkylenes) is polyethylene glycol.Polyethylene glycol preferably has a number average molecular weight of50 to 20000, more preferably 1000 to 15000, still more preferably 2000to 9500. The number average molecular weight of the polyethylene glycolis a value calculated from the hydroxyl value determined in conformitywith JIS K0070.

Preferred among the aliphatic polyesters is polycaprolactone.Polycaprolactone preferably has a number average molecular weight of1000 to 32000, more preferably 2000 to 10000, still more preferably 2000to 4000.

The amount of the surfactant contained is preferably 1 to 99 mass %,more preferably 5 to 90 mass %, still more preferably 10 to 80 mass %,particularly preferably 20 to 70 mass %, in the processing aid.

The amount of the surfactant is also preferably 50 mass % or more, morepreferably more than 50 mass %.

The processing aid of the present invention may contain ananti-reagglomerating agent. Containing the anti-reagglomerating agentrestrains reagglomeration of the polymer.

The anti-reagglomerating agent is preferably a powder of an inorganiccompound. For example, the anti-reagglomerating agent is preferablypowder of an inorganic compound to be mentioned hereinbelow as anexample of a filler, a colorant, or an acid acceptor.

the anti-reagglomerating agent used may be one usually used as a filler,a colorant, an acid acceptor, or the like.

Examples of the filler include barium sulfate, calcium carbonate,graphite, talc, and silica.

Examples of the colorant include metal oxides such as titanium oxide,iron oxide, and molybdenum oxide.

Examples of the acid acceptor include magnesium oxide, calcium oxide,and lead oxide.

The anti-reagglomerating agent is preferably the filler. Theanti-reagglomerating agent is more preferably at least one selected fromthe group consisting of talc, silica, and calcium carbonate.

The anti-reagglomerating agent is preferably powder having an averageparticle size of 0.01 μm or greater and 50 μm or smaller. The averageparticle size of the powder is more preferably 0.05 μm or greater and 30μm or smaller, still more preferably 0.1 μm or greater and 10 μm orsmaller. The average particle size of the anti-reagglomerating agent isa value determined in conformity with ISO 13320-1.

The anti-reagglomerating agent may be surface-treated with a couplingagent, if necessary.

The amount of the anti-reagglomerating agent is preferably 1 to 30 partsby mass, more preferably 3 to 20 parts by mass, still more preferably 5to 15 parts by mass, relative to 100 parts by mass of the polymer.

The anti-reagglomerating agent may include one species thereof or two ormore species thereof.

The processing aid of the present invention may further contain anyadditive such as antioxidants, ultraviolet absorbers, and flameretardants in addition to the above components.

The molding composition of the present invention contains amelt-fabricable resin and the aforementioned processing aid of thepresent invention. The melt-fabricable resin herein means a polymerwhose melt flow is determinable at a temperature higher than thecrystalline melting point in conformity with ASTM D-1238 and D-2116.

The melt-fabricable resin may be any resin, and preferably afluorine-free resin. Examples thereof include polyolefin resins such aspolyethylene and polypropylene; polyamide (PA) resins such as nylon 6,nylon 11, nylon 12, nylon 46, nylon 66, nylon 610, nylon 612, and nylonMXD6; polyesters such as polyethylene terephthalate (PET), polybutyleneterephthalate (PBT), polyarylates, aromatic polyesters (including liquidcrystal polyesters), and polycarbonate (PC); polyacetal (POM) resin;polyether resins such as polyphenylene oxide (PPO), modifiedpolyphenylene ether, and polyether ether ketone (PEEK); polyamide imide(PAI) resins such as polyamino bismaleimide; polysulfone resins such aspolysulfone (PSF) and polyether sulfone (PES); vinyl polymers such asABS resin and poly 4-methylpentene-1 (TPX resin); polyphenylene sulfide(PPS); polyketone sulfide; polyether imide; and polyimide (PI). Thenylon MXD6 is a crystallizable polycondensation product obtainable frommethaxylene diamine (MXD) and adipic acid.

The melt-fabricable resin is preferably a polyolefin resin and/or a PAresin, more preferably a polyolefin resin.

For easy melt fabrication, the melt-fabricable resin in the moldingcomposition is preferably a thermoplastic resin. The molding compositionof the present invention may contain one or two or more of the abovemelt-fabricable resins.

The melt-fabricable resin preferably has a melt-fabricable temperatureof 100° C. to 350° C. The melt-fabricable resin may or may not havecrystallizability.

The melt-fabricable resin, if having crystallizability, preferably has amelting point of 80° C. to 300° C., more preferably 100° C. to 200° C.The melt-fabricable resin, if having no crystallizability, preferablyhas a fabricable temperature which is substantially equal to that of acrystallizable melt-fabricable resin whose melting point range is known.The melting point of the crystallizable melt-fabricable resin can bedetermined using a DSC device.

The melt-fabricable resin can be synthesized by a conventionally knownmethod in accordance with the type thereof, for example.

The melt-fabricable resin may be in the form of powder, granules,pellets, or the like. In order to efficiently melt the melt-fabricableresin in the resulting molding composition and to disperse theprocessing aid therein, the melt-fabricable resin is preferably in theform of pellets.

The molding composition of the present invention preferably contains thepolymer in an amount of 0.0001 to 10 mass % of the sum of the masses ofthe processing aid containing the polymer and the melt-fabricable resin.

The amount of the polymer is more preferably 0.001 mass % or more, whilemore preferably 5 mass % or less, still more preferably 0.5 mass % orless, of the sum of the masses of the processing aid containing thepolymer and the melt-fabricable resin.

The molding composition may be prepared by adding the processing aid ofthe present invention itself to the melt-fabricable resin, or may beprepared by adding the processing aid in the form of the processing aidmasterbatch to be mentioned later to the melt-fabricable resin.

The molding composition of the present invention may further containother components, if necessary, in addition to the processing aid andthe melt-fabricable resin.

Examples of the components include reinforcing materials such as glassfibers and glass powder; stabilizers such as minerals and flakes;lubricants such as silicone oil and molybdenum disulfide; pigments suchas titanium dioxide and red iron oxide; conductive agents such as carbonblack; impact-resistance improvers such as rubber; antioxidants such ashindered phenol antioxidants and phosphorus antioxidants; core-formingagents such as metal salts and acetals of sorbitol; and other additivesrecorded in the positive list that is formulated as voluntary standardsby Japan Hygienic Olefin And Styrene Plastics Association.

The processing aid masterbatch of the present invention contains theaforementioned processing aid of the present invention and themelt-fabricable resin. The processing aid masterbatch of the presentinvention can be suitably used as a processing aid in molding themelt-fabricable resin.

In the processing aid masterbatch of the present invention, the polymeris uniformly dispersed in the melt-fabricable resin. Thus, adding themasterbatch in molding the melt-fabricable resin leads to improvement ofthe molding processability, such as decreases in extrusion torque andextrusion pressure.

Examples of the melt-fabricable resin include the same melt-fabricableresins as mentioned above, and the melt-fabricable resin is preferably apolyolefin resin, more preferably polyethylene.

The processing aid masterbatch of the present invention may be in anyform such as powder, granules, pellets, or the like. In order to keepthe polymer in the state of being finely dispersed in themelt-fabricable resin, the masterbatch is preferably in the form ofpellets obtainable by melt-kneading.

For easy melt fabrication, the processing aid masterbatch of the presentinvention preferably contains the polymer in an amount higher than 0.1mass % but not higher than 20 mass % of the sum of the masses of themelt-fabricable resin and the processing aid containing the polymer. Thelower limit of the amount of the polymer is more preferably 0.3 mass %,still more preferably 0.6 mass %, of the sum of the masses, whereas theupper limit thereof is more preferably 10 mass %.

The processing aid masterbatch of the present invention may furthercontain other components, if necessary, in addition to the processingaid and the melt-fabricable resin.

The components may be any components, and examples thereof include thosementioned for the molding composition of the present invention.

The processing aid masterbatch of the present invention may beobtainable by kneading, at 100° C. to 350° C., a matter prepared byadding the processing aid and other desired components to themelt-fabricable resin. For good dispersibility of the polymer, themasterbatch is preferably one obtainable by adding the above processingaid prepared in advance to the melt-fabricable resin and kneading thecomponents within the above temperature range.

The molded article of the present invention is obtainable by molding themolding composition of the present invention.

The molding may be performed by preparing the molding composition of thepresent invention in advance, putting the composition into a moldingdevice, and then melting and extruding the composition, or may beperformed by putting the above processing aid and melt-fabricable resininto a molding device at once, and then melting and extruding thecomponents, or may be performed by putting the above processing aidmasterbatch and melt-fabricable resin into a molding device at once, andthen melting and extruding the components.

The molding composition may be molded by any method such as extrusionmolding, injection molding, or blow molding. In order to effectivelyenjoy the molding processability, extrusion molding is preferred.

The molding may be performed under any conditions, and the conditionsmay be appropriately adjusted in accordance with the composition andamount of the molding composition to be used, the shape and size of adesired molded article, and other factors.

The molding temperature is usually not lower than the melting point ofthe melt-fabricable resin in the molding composition but lower than thelower temperature selected from the decomposition temperatures of theprocessing aid and the melt-fabricable resin, and is within the range of100° C. to 350° C.

In the case of extrusion molding, the molding temperature is alsoreferred to as the extrusion temperature.

The present invention also relates to a method of extruding a moldingcomposition, including adding the processing aid to the melt-fabricableresin to provide a molding composition and extruding the moldingcomposition.

The molded article of the present invention may have any of variousshapes, such as a sheet shape, a film shape, a rod shape, a pipe shape,or a fibrous shape.

The molded article may be used in any application in accordance with thetype of the melt-fabricable resin used. For example, the molded articlecan be suitably used in applications strongly requiring mainly physicalproperties, such as mechanical properties, and surface properties.

Examples of the applications of the molded article include films, bags,coating materials, tablewares such as containers for beverages, cables,pipes, fibers, bottles, gasoline tanks, and other molded articles invarious industries.

EXAMPLES

The present invention will be more specifically described referring toexamples and comparative examples.

Still, the invention is not limited to these examples.

The measured values described in the following examples and comparativeexamples are values determined by the following methods.

1. Composition of Copolymer

The composition of the copolymer was determined using a ¹⁹F-NMR device(AC300P, Bruker Corp.).

2. Melt Flow Rate (MFR)

The melt flow rate was determined in conformity with ASTM D-3159.

The MFR of Fluorine-containing Polymers 2 and 3, Fluorine-containingPolymer 1, PVDF 1, and PVDF 2 were respectively determined at 250° C.and 98 N, at 230° C. and 98 N, at 230° C. and 198 N, and at 230° C. and98 N.

3. Melting Point (mp)

The temperature corresponding to the maximum value on a heat-of-fusioncurve obtained using a DSC device (Seiko Instruments Inc.) at atemperature-increasing rate of 10° C./min was defined as the meltingpoint.

4. Melt Fracture Disappearance Time

A polyolefin alone was extruded until the pressure was stabilized withmelt fracture occurring on the entire surface. At the time when thescrew of the extruder became visible, the materials such as a processingaid of the corresponding composition were put into a hopper. This timingwas defined as 0. Then, the period of time from 0 to the time when themelt fracture disappeared and the entire surface of the molded articlebecame smooth was defined as the melt fracture disappearance time. Thedisappearance of the melt fracture was confirmed by visual observationand touch examination.

If the visual observation and touch examination confirm that the entiresurface does not have a gloss, smooth surface with no melt fracture buthave a stripe-like, entirely or partially undulated surface, this stateis called “shark skin” herein.

5. Pressure Decrease

In the extrusion evaluation to be mentioned later, the extrusion startswith an initial extrusion pressure observed when linear low-densitypolyethylene alone is used without addition of a processing aid (initialpressure). The pressure is then decreased as the processing aid is addedand the effects thereof are exerted, and finally the pressure isstabilized at substantially a constant pressure (stabilized pressure).The difference between the initial pressure and the stabilized pressurewas defined as the pressure decrease.

If the pressure was not stabilized within the set period of time, thedifference between the initial pressure and the pressure at the finishtime was defined as the pressure decrease.

(Production of Processing Aids)

Processing aids used in Examples 1 to 3 were prepared by the followingmethod.

Fluorine-containing Polymers 1 to 3 were produced in substantially thesame manner as in the polymerization methods of Examples 1 and 2disclosed in JP S63-59405 B and the polymerization method of theexamples disclosed in JP S62-21805 B. Table 1 shows the compositions ofFluorine-containing Polymers 1 to 3.

Separately, talc (Jetfine 1A, Luzenac), silica (SYLOBLOC 45H, Grace &Co.), and calcium carbonate (Brilliant 1500, Shiraishi Kogyo Kaisha,Ltd.) were mixed in a mass ratio of 3/6/2 to prepare ananti-reagglomerating agent.

Then, one of Fluorine-containing Polymers 1 to 3 and theanti-reagglomerating agent were mixed in a mass ratio of 90/10 toprovide a processing aid.

TABLE 1 Composition of fluorine-containing polymer (mol %) ElastomericProportion Melting segment (SS) Non-elastomeric segment (HS) of SS pointMFR TFE VDF HFP TFE Ethylene HFP VDF (%) (° C.) (g/10 min)Fluorine-containing Polymer 1 20 50 30 0 0 0 100 85 165 3Fluorine-containing Polymer 2 20 50 30 49 43 8 0 85 233 19Fluorine-containing Polymer 3 20 50 30 49 43 8 0 75 232 6

The abbreviations in Table 1 mean as follows.

TFE: tetrafluoroethylene

VDF: vinylidene fluoride

HFP: hexafluoropropylene

The processing aid used in Comparative Example 1 was prepared by thefollowing method.

A VDF/HFP copolymer (FKM) (VDF/HFP=78/22 mol %, Mooney viscosity: 40)was produced in substantially the same manner as in the polymerizationmethod of the examples disclosed in JP 5140902 B.

Separately, talc (Jetfine 1A, Luzenac), silica (SYLOBLOC 45H, Grace &Co.), and calcium carbonate (Brilliant 1500, Shiraishi Kogyo Kaisha,Ltd.) were mixed in a mass ratio of 3/6/2 to prepare ananti-reagglomerating agent.

Then, the FKM and the anti-reagglomerating agent were mixed in a massratio of 90/10 to provide a processing aid.

The processing aid used in Comparative Example 2 was prepared by thefollowing method.

A VDF/HFP copolymer (FKM) (VDF/HFP=78/22 mol %, Mooney viscosity: 40)was produced in substantially the same manner as in the polymerizationmethod of the examples disclosed in JP 5140902 B.

The FKM and polyethylene glycol (CARBOWAX™ SENTRY™ POLYETHYLENE GLYCOL8000 GRANULAR, The Dow Chemical Company, hereinafter, referred to as“PEG”) were mixed in a mass ratio of 1/2 to provide a processing aid.

In Comparative Example 3, a PVDF homopolymer (melting point: 159° C.,MFR: 4.4) (hereinafter, referred to as “PVDF 1”) produced by a knownemulsion polymerization method was used as a processing aid.

In Comparative Example 4, modified PVDF (HFP 4.5 mol %, melting point:144° C., MFR: 1.1) (hereinafter, referred to as “PVDF 2”) produced by aknown emulsion polymerization method was used as a processing aid.

(Production of Masterbatch)

The processing aid was mixed with linear low-density polyethylene (LLDPE1002YB, ExxonMobil Corp.) such that the amount of the processing aid was5 wt % relative to the sum of the weights of the linear low-densitypolyethylene and the processing aid, and then 0.1 wt % of IRGANOX B225(BASF) was mixed therewith. The mixture was put into a twin-screwextruder (Labo Plastomill 30C150, screw L/D, Toyo Seiki Seisakusho,Ltd.) and was processed at a screw rotational speed of 80 rpm. Thereby,pellets containing the processing aid were obtained. In order to improvethe dispersion homogeneity of the processing aid in the resultingmasterbatch, the obtained pellets containing the processing aid weremixed using a tumbler mixer and the mixture was processed at a screwrotational speed of 100 rpm, while the other conditions were the same asfor providing the pellets. Thereby, a processing aid-containingmasterbatch containing the processing aid and the polyolefin wasobtained.

(1) The temperature conditions in extrusion of Fluorine-containingPolymers 1 and 2 were as follows.

Condition 1: cylinder temperature=150° C., 250° C., and 250° C.; dietemperature=180° C.

(2) The temperature conditions in extrusion of Fluorine-containingPolymer 3, FKM, and FKM+PEG were as follows.

Condition 2: cylinder temperature=150° C., 170° C., and 180° C.; dietemperature=180° C.

(3) The temperature conditions in extrusion of PVDF 1 and PVDF 2 were asfollows.

Condition 3: cylinder temperature=150° C., 180° C., and 190° C.; dietemperature=180° C.

An ultrathin slice was cut out of the resulting pellets and wasmicroscopically observed using a reflected light microscope. Theresulting image was binarized using an optical analyzer. This confirmedthat, in the respective masterbatches, the processing aid in the form offine particles was dispersed in the linear low-density polyethylene inthe resulting pellets. In each case, the average dispersed particle sizethereof, determined on the binarized image, was 5 μm or smaller.

(Extrusion Evaluation 1)

Example 1

The masterbatch containing 5 wt % Fluorine-containing Polymer 1 wasadded to and tumble-mixed with linear low-density polyethylene (LLDPE1201XV, ExxonMobil Corp.) such that the amount of the masterbatch was 1wt % relative to the sum of the weights of the linear low-densitypolyethylene and the masterbatch. The resulting masterbatch-containinglinear low-density polyethylene was extruded using a single screwextruder (Rheomex OS, HAAKE, L/D: 33, screw diameter: 20 mm, diediameter: 2 mmϕ×40 mmL) at a cylinder temperature of 210° C. to 240° C.,a die temperature of 240° C., and a screw rotational speed of 80 rpm.The die pressure change and the melt fracture change were observed.

Example 2

Extrusion evaluation was performed in the same manner as in Example 1except that masterbatch containing 5 wt % Fluorine-containing Polymer 2was added.

Example 3

Extrusion evaluation was performed in the same manner as in Example 1except that masterbatch containing 5 wt % Fluorine-containing Polymer 3was added.

Comparative Example 1

Extrusion evaluation was performed in the same manner as in Example 1except that masterbatch containing 5 wt % FKM was added.

Comparative Example 2

Extrusion evaluation was performed in the same manner as in Example 1except that masterbatch containing 5 wt % FKM+PEG was added.

Comparative Example 3

Extrusion evaluation was performed in the same manner as in Example 1except that masterbatch containing 5 mass % PVDF 1 was added.

Comparative Example 4

Extrusion evaluation was performed in the same manner as in Example 1except that masterbatch containing 5 wt % PVDF 2 was added.

Before the experiments, the extruder was purged for about 15 minutes byputting linear low-density polyethylene containing 15 wt % silica into ahopper and increasing the screw rotational speed up to 150 rpm. Then,the extruder was further purged for about 15 minutes using the samelinear low-density polyethylene (LLDPE 1201XV, ExxonMobil Corp.) as usedin the experiments. Thereafter, the screw rotational speed was returnedto 80 rpm and extrusion was performed until the temperature wasstabilized. After confirmation of return of the initial pressure to 35.5to 36.3 MPa, the next experiment was performed. If the initial pressuredid not return to this range, the above purging procedure was repeateduntil the initial pressure returned to the range, and then the nextexperiment was performed.

Table 2 shows the evaluation results and other data in Examples 1 to 3and Comparative Examples 1 to 4. FIG. 1 shows the die pressure changesover time in the extrusion processes of Examples 1 to 3 and ComparativeExamples 1 to 4.

TABLE 2 Processing aid Amount of pressure Melt fracture Appearance ofPolymer Anti-reagglomerating decreased (ΔP) disappearance time extrudateafter (+surfactant) agent (MPa) (min) experiment Example 1Fluorine-containing Talc/silica/calcium 5.7 20 Glossy Polymer 1carbonate Example 2 Fluorine-containing Talc/silica/calcium 5.7 20Glossy Polymer 2 carbonate Example 3 Fluorine-containingTalc/silica/calcium 5.6 20 Glossy Polymer 3 carbonate Comparative FKMTalc/silica/calcium 4.7 70 or longer Shark skin Example 1 carbonateComparative FKM (+PEG) — 4.4 70 or longer Shark skin Example 2Comparative PVDF 1 — 4.5 50 Glossy Example 3 Comparative PVDF 2 — 5.2 50Glossy Example 4

The shear rate calculated by the following formula 1 was about 1,200sec⁻¹.

$\begin{matrix}{\gamma = \frac{4Q}{\pi\; R^{3}}} & \left( {{Formula}\mspace{14mu} 1} \right)\end{matrix}$

The abbreviations in the formula represent the following.

γ: shear rate (sec⁻¹)

Q: amount of matter extruded (kg/hr)

R: diameter of die (mm)

Table 2 and FIG. 1 show the following. In Examples 1 to 3, the pressuredecrease (amount ΔP of pressure decreased) was as large as 5.6 to 5.7MPa, and the melt fracture completely disappeared. In ComparativeExamples 1 and 2, the pressure decrease (amount ΔP of pressuredecreased) was smaller than that in Examples 1 to 3, and the meltfracture did not completely disappear even after 70 minutes from thestart of adding the masterbatch. In Comparative Examples 3 and 4, thepressure decrease (amount ΔP of pressure decreased) was smaller thanthat in Examples 1 to 3, and the period of time until the melt fracturecompletely disappeared was 50 minutes, i.e., became longer.

As mentioned above, the processing aids used in Examples 1 to 3 have agreat effect of improving the moldability in molding at a high shearrate.

(Extrusion Evaluation 2)

Example 4

The masterbatch used in Example 1 was added to and tumble-mixed withlinear low-density polyethylene (LLDPE 1201XV, ExxonMobil Corp.) suchthat the amount of the masterbatch was 1 wt % relative to the sum of theweights of the linear low-density polyethylene and the masterbatch. Theresulting mixture was extruded using a single screw extruder (RheomexOS, HAAKE, L/D: 33, screw diameter: 20 mm, die diameter: 2 mmϕ×40 mmL)at a cylinder temperature of 210° C. to 240° C., a die temperature of240° C., and a screw rotational speed of 10 rpm. The die pressure changeand the melt fracture change were observed.

Comparative Example 5

Extrusion evaluation was performed in the same manner as in Example 4except that the masterbatch used in Comparative Example 1 was added.

Comparative Example 6

Extrusion evaluation was performed in the same manner as in Example 4except that the masterbatch used in Comparative Example 2 was added.

Comparative Example 7

Extrusion evaluation was performed in the same manner as in Example 4except that the masterbatch used in Comparative Example 3 was added.

Comparative Example 8

Extrusion evaluation was performed in the same manner as in Example 4except that the masterbatch used in Comparative Example 4 was added.

Before the experiments, the extruder was purged for about 15 minutes byputting linear low-density polyethylene containing 15 wt % silica into ahopper and increasing the screw rotational speed up to 150 rpm. Then,the extruder was further purged for about 15 minutes using the samelinear low-density polyethylene (LLDPE 1201XV, ExxonMobil Corp.) as usedin the experiments. Thereafter, the screw rotational speed was returnedto 80 rpm and extrusion was performed until the temperature wasstabilized. After confirmation of return of the initial pressure to 14.3to 14.8 MPa, the next experiment was performed. If the initial pressuredid not return to this range, the above purging procedure was repeateduntil the initial pressure returned to the range, and then the nextexperiment was performed.

Table 3 shows the evaluation results and other data in Example 4 andComparative Examples 5 to 8. FIG. 2 shows the die pressure changes overtime in the extrusion processes of Example 4 and Comparative Examples 5to 8.

TABLE 3 Processing aid Amount of pressure Melt fracture Appearance ofPolymer Anti-reagglomerating decreased (ΔP) disappearance time extrudateafter (+surfactant) agent (MPa) (min) experiment Example 4Fluorine-containing Talc/silica/calcium 3.0 60 Glossy Polymer 1carbonate Comparative FKM Talc/silica/calcium 0.1 70 or longer Sharkskin Example 5 carbonate Comparative FKM (+PEG) — 0.1 70 or longer Sharkskin Example 6 Comparative PVDF 1 — 0.4 60 Glossy Example 7 ComparativePVDF 2 — 0.2 60 Glossy Example 8

The shear rate calculated by the above formula 1 was about 130 sec⁻¹.

Table 3 and FIG. 2 show the following. In Example 4, the pressuredecreased by 3.0 MPa within 15 minutes from the start of adding themasterbatch, and the melt fracture completely disappeared within 60minutes. In Comparative Examples 5 and 6, substantially no pressuredecrease (amount ΔP of pressure decreased) was observed, and the meltfracture did not completely disappear even after 70 minutes from thestart of adding the masterbatch. In Comparative Examples 7 and 8,substantially no pressure decrease (amount ΔP of pressure decreased) wasobserved as in Comparative Examples 5 and 6 although the melt fracturecompletely disappeared within 60 minutes.

(Extrusion Evaluation 3)

Example 5

The masterbatch used in Example 1 was added to and tumble-mixed withhigh-density polyethylene (Vestolen A 6060R black, SABIC) such that theamount of the masterbatch was 1 wt % relative to the sum of the weightsof the high-density polyethylene and the masterbatch. The resultingmixture was extruded using a single screw extruder (Rheomex OS, HAAKE,L/D: 33, screw diameter: 20 mm, die diameter: 2 mmϕ×40 mmL) at acylinder temperature of 170° to 200° C., a die temperature of 200° C.,and a screw rotational speed of 10 rpm. The die pressure change wasobserved.

No melt fracture occurred under such molding conditions.

Comparative Example 9

Extrusion evaluation was performed in the same manner as in Example 5except that the masterbatch used in Comparative Example 1 was added.

Comparative Example 10

Extrusion evaluation was performed in the same manner as in Example 5except that the masterbatch used in Comparative Example 2 was added.

Comparative Example 11

Extrusion evaluation was performed in the same manner as in Example 5except that the masterbatch used in Comparative Example 3 was added.

Comparative Example 12

Extrusion evaluation was performed in the same manner as in Example 5except that the masterbatch used in Comparative Example 4 was added.

Before the experiments, the extruder was purged for about 15 minutes byputting high-density polyethylene containing 15 wt % silica into ahopper and increasing the screw rotational speed up to 150 rpm. Then,the extruder was further purged for about 15 minutes using the samehigh-density polyethylene as used in the experiments. Thereafter, thescrew rotational speed was returned to 10 rpm and extrusion wasperformed until the temperature was stabilized. After confirmation ofreturn of the initial pressure to 14.3 to 14.8 MPa, the next experimentwas performed. If the initial pressure did not return to this range, theabove purging procedure was repeated until the initial pressure returnedto the range, and then the next experiment was performed.

Table 4 shows the evaluation results and other data in Example 5 andComparative Examples 9 to 12. FIG. 3 shows the die pressure changes overtime in the extrusion processes of Example 5 and Comparative Examples 9to 12.

TABLE 4 Processing aid Amount Anti- of pressure Polymer reagglomeratingdecreased (ΔP) (+surfactant) agent (MPa) Example 5 Fluorine-containingTalc/silica/calcium 3.7 Polymer 1 carbonate Comparative FKMTalc/silica/calcium 2.0 Example 9 carbonate Comparative FKM (+PEG) — 2.4Example 10 Comparative PVDF 1 — 2.0 Example 11 Comparative PVDF 2 — 1.4Example 12

The shear rate calculated by the above formula 1 was about 130 sec⁻¹.

Table 4 and FIG. 3 show the following. In Example 5, the pressuredecrease (amount ΔP of pressure decreased) was greater than that inComparative Examples 9 to 12, and thus the processing aid exerts theeffects thereof even in molding high-density polyethylene at a lowtemperature and a low shear rate.

(Extrusion evaluation 4)

Example 6

The masterbatch used in Example 1 was added to and tumble-mixed withhigh-density polyethylene (Vestolen A 6060R black, SABIC) such that theamount of the masterbatch was 1 wt % relative to the sum of the weightsof the high-density polyethylene and the masterbatch. The resultingmixture was extruded using a single screw extruder (Rheomex OS, HAAKE,L/D: 33, screw diameter: 20 mm, die diameter: 2 mmϕ×40 mmL) at acylinder temperature of 200° to 230° C., a die temperature of 230° C.,and a screw rotational speed of 10 rpm. The die pressure change wasobserved.

No melt fracture occurred under such molding conditions.

Comparative Example 13

Extrusion evaluation was performed in the same manner as in Example 6except that the masterbatch used in Comparative Example 1 was added.

Comparative Example 14

Extrusion evaluation was performed in the same manner as in Example 6except that the masterbatch used in Comparative Example 2 was added.

Comparative Example 15

Extrusion evaluation was performed in the same manner as in Example 6except that the masterbatch used in Comparative Example 3 was added.

Comparative Example 16

Extrusion evaluation was performed in the same manner as in Example 6except that the masterbatch used in Comparative Example 4 was added.

Before the experimental operations, the extruder was purged for about 15minutes by putting high-density polyethylene containing 15 wt % silicainto a hopper and increasing the screw rotational speed up to 150 rpm.Then, the extruder was further purged for about 15 minutes using thesame high-density polyethylene as used in the experiments. Thereafter,the screw rotational speed was returned to 10 rpm and extrusion wasperformed until the temperature was stabilized. After confirmation ofreturn of the initial pressure to 13.6 to 14.2 MPa, the next experimentwas performed. If the initial pressure did not return to this range, theabove purging procedure was repeated until the initial pressure returnedto the range, and then the next experiment was performed.

Table 5 shows the evaluation results and other data in Example 5 andComparative Examples 13 to 16. FIG. 4 shows the die pressure changesover time in the extrusion processes of Example 6 and ComparativeExamples 13 to 16.

TABLE 5 Processing aid Amount Anti- of pressure Polymer reagglomeratingdecreased (ΔP) (+surfactant) agent (MPa) Example 6 Fluorine-containingTalc/silica/calcium 3.5 Polymer 1 carbonate Comparative FKMTalc/silica/calcium 2.5 Example 13 carbonate Comparative FKM (+PEG) —1.5 Example 14 Comparative PVDF 1 — 2.5 Example 15 Comparative PVDF 2 —2.3 Example 16

The shear rate calculated by the above formula 1 was about 130 sec⁻¹.

Table 5 and FIG. 4 show the following. In Example 6, the pressuredecrease (amount ΔP of pressure decreased) was greater than that inComparative Examples 13 to 16.

The above results prove that Fluorine-containing Polymer 1 exerts theeffect of improving the processability within a molding temperaturerange used in molding high-density polyethylene into large-diameterpipes at a low shear rate.

The invention claimed is:
 1. A molding composition comprising aprocessing aid, and a polyolefin resin, the processing aid comprising apolymer containing a fluorine-containing elastomeric polymer segment anda fluorine-containing non-elastomeric polymer segment, and the polymerbeing contained in an amount of 0.0001 to 10 mass % of the sum of massesof the processing aid and the polyolefin resin.
 2. A molded articleobtainable by molding the molding composition according to claim 1.